Since the start of the industrial revolution, the reciprocating piston engine based on the Otto and Diesel cycles and, the gas turbine engine based on the Brayton cycle, have largely dominated the market. Despite this fact, for many years, patents on rotary combustion engines have claimed that rotary engines possess many advantages over reciprocating engines such as having high torque, fewer parts, lower weight and fewer reciprocating imbalance. Fundamental design characteristics is of the present invention addresses the main problems related to rotary engines and bridges the mass flow and rotational speed gaps between reciprocating and gas turbine engines.
Avoiding Wear and Improving Sealing in a Vane Rotary Engine
One reason for the lack of industrial attention is that many rotary engines have been faced by serious wear and sealing deficiencies. The main cause of the wear is the centrifugal force generated during high speed rotation that forces the vanes to scrap the inner peripheral of the working chamber. This has been recently addressed by using hinged vane central retention mechanisms (U.S. Pat. No. 5,352,295, Chou Yi, Oct. 4, 1994 and PCT WO 02/31318, VADING Kjell, Apr. 18, 2002). In such configurations, the sliding vane is articulated through a cylindrical slideable guidance placed between the rotor and the vane. While correcting the wear problem, the number of moving parts has increased and hence, the system became more complex. At worst, each one of said parts increases the probability of engine failure due to wear and fatigue. At best, the pressure sealing, lubrication and cooling capabilities of the vane mechanism deteriorates. In the present invention, the intermediary cylindrical slides are eliminated all together as the radially outer vane tips (86,109) are always in a natural contact with the housing inner peripheral (88,97). The basic reason for this natural contact is that the housing inner peripheral (88,97) is non-circular and has a cycloidal shape (FIG. 6) that accommodates perfectly an eccentrically placed sliding vane of fixed length (16,37,50,63,87,100,119, 125). The easy machining and manufacturing technique disclosed in this invention, is based on the side enlargement of the largest fitting circle within the cycloid (FIG. 6), and have not been mentioned by prior arts (U.S. Pat. No. 6,236,897, LEE and al., May 22, 2001; U.S. Pat. No. 5,996,355, Jirnov and al., Dec. 7, 1999, U.S. Pat. No. 4,422,419, UMEDA, Dec. 27, 1983). The said geometry (FIG. 6), given in the detailed description and the related claims of the invention below, has good sealing at all sliding vane position angles. Wear contacts generated by the sliding is vane tips (86,109) against the housing inner peripheral (88) are eliminated by a pivot axle vane retention mechanism (54, 55, 61, 62, 81, 82, 104, 105) centrally placed within the rotor.
Rotary Engines with Sliding Vane Slicing Through Rotor
Instead of having hinged vanes, some of the prior arts do use sliding vanes slicing through the rotor (U.S. Pat. No. 4,414,938, UMEDA Soei, Nov. 15, 1983 and U.S. Pat. No. 4,422,419, UMEDA Soei, Dec. 27, 1983; U.S. Pat. No. 5,596,963, LAI, Jui, H., Jan. 28, 1997). In these arts, a plurality of spring-loaded vanes are used against the housing wall to achieve air-tightness. Therefore, they fundamentally differ from the springless single “all-through solid” vane mechanism of the present invention. Furthermore, above-mentioned prior arts do not have any central vane retention mechanism (138, 139, 150) that would prevent the related wear problem. Moreover, only a portion of the entire inner peripheral of the housing is elliptic. Another patent, related to rotary heat engine with ‘all-through solid’ vane (U.S. Pat. No. 5,511,525, JIRNOV and al., Apr. 30, 1996), uses at least two mutually perpendicular vanes with radially extending guide. The plural use of vanes within one compressor housing substantially reduces the pressure ratio. This leads to a reduction of the rotary component efficiency and also increase the system complexity as more stage is required. Furthermore, the vane guide path mechanism described in this prior art is an additional cause for increased friction wear.
Rotary Engines with Separate Compression and Expansion Chambers
There are many rotary engine patents which provide separate compression, combustion and expansion chambers (PCT WO 02/31318, VADING Kjell, Apr. 18, 2002; PCT WO 99/041141, O'BRIEN Kevin, Jan. 28, 1999; U.S. Pat. No. 5,596,963, LAI, Jui, H., Jan. 28, 1997; U.S. Pat. No. 5,335,497, MACOMBER Bennie D., Aug. 9, 1994; U.S. Pat. No. 5,352,295, YI Chou, Oct. 4, 1994; U.S. Pat. No. 5,235,945, TESTEA Goerge, Aug. 17, 1993). Actually, almost all rotary vane type engines produce very high torque because the combusted gas expands right against the hot section vane (37,63,100,119), which is the arm length of the generated torque. Therefore, not only is the crankshaft unnecessary, but when comparing engines of equal volumes, the power leverage on the drive shaft of a rotary engine is greater than that of a corresponding reciprocating engine. However, here too, there is room for improvement; the present invention overcomes the drawbacks and limitations of todays power and refrigeration cycles by proposing and implementing new high efficiency thermodynamic cycles (151abceh, 151abcdfh, 151abcgh)
Rotary Engine with Improved Thermodynamic Cycle
The present invention combines the advantages of Otto and Diesel cycles at intake, compression and combustion phases of the thermodynamic cycle by limiting the peak combustion temperature. The present invention also claims an expanded power stroke that greatly improves power extraction and efficiency. With a proper thermodynamic and geometrical match of the compressor and turbine working chambers, it is shown that the expansion process can be improved and lower exhaust pressure and temperature levels can be achieved. A search of the prior art did not disclose any rotary engine patent with separate compression and expansion chambers that considers and provides an expansion process that would take the combusted products further down to ambient pressure levels. The overlook of such thermodynamic cycle improvement is a major source of wasted energy that ultimately translates in engine fuel inefficiency. Accordingly, the present invention provides proper sizing of the compression and expansion chambers, the rotors, and the vanes so as to achieve optimum compression (151ab), combustion (151bce, 151bcdf, 151bcg) and expansion (151eh, 151fh, 151gh).